Wire coating die



June 23, 1942. l. H. WILSON ET AL 2,287,589

WIRE COATING DIE Filed July 17, '1940 Inve t Alexander GQBeaVer,

Their- Attohneg.

Patented June 23,1942

. Mass, assignors to General Electric a corporation ol' New York Company,

Application Jill! 17, 1940, Serial No. 345,992

. sulating varnish are ordinarily .applied to each GCIaims.

This invention relates to apparatus for coat ing elongated articles. such as wire and the like, of rectangular cross-section with liquid coating compositions, for example, enamels, varnishes, lacquers, etc. The invention is especially concerned with the novel applicator or die hereinafter, for brevity, referred to as a die, by the use of which wires or other elongated articles of rectangular or square cross-section, hereinafter referred to as of rectangular or substantially rectangular cross-section, may be efiectively and economically coated with liquid coating compositions including a viscous solution of a resinous composition obtained by condensing an aldehyde, such as formaldehyde, with the hydrolysis prod not of a polyvinyl ester such .as polyvinyl acetate.

The novel features of our invention are set forth in .the appended claims. The invention itself, however, will be understood more readilyby reference to the following more detailed description when considered in connection with the accompanying drawing wherein Fig. 1 is a view showing somewhat schematically coating apparatus embodying the invention; Fig. 2 is a top view of one form of die embodying the invention; Fig.

3 is a perspective view of portions of the die shown in Fig. 2 before assembly; Fig. 4 is a, top view of a modified form of die embodying the,invention; Fig. 5 is a perspective view of some of the elements of the die shown in Fig. 4; and Fig.

' 6 is a perspective view of another embodiment of cross-section through an ordinary pair of rolls or through turks-head rolls, the resultant prod not is not always of uniform or constant crosswire, it is thus usually necessary to .use a series of dies, each die having an opening correspondingly larger than that of the previous die by the total thickness of the baked coating applied to employed in coating wires of different sizes as well as the same wire having different thicknesses of baked enamel thereon. The die is easily assembled about the wire and removed therefrom and, in addition to being self-conforming, that is, adapted to follow variations in the cross-sectional size or shape. of the rectangular wire; it is also self-centering on the wire thus permitting the application of a layer of coating material of equal and uniform thickness on all four sides of the rectangular or square wire.

The manner in which our invention may be applied toj conventional wire coating apparatus is schematically illustrated in Fig. 1. As shown in this figure a. wire I is drawn from a pay-off reel removing excess coating material from the freshly coated wire, specific embodiments thereof section. The insulation of such wire by means of ordinary rigid dies is usually impractical as any die large enough to pass the larger or thicker portions of the wire will apply too thick a' layer of enamel or varnish to those portions of the wire of smaller or thinner cross-section. Even in the insulation of rectangular wires of substantially uniform cross-section, it is necessary to have a of a :few thousandths of an inch in order that a.

film, of enamel of proper thickness may be applied to the wire. As a number of layersor films of in- 55 die and oven to receive additional layers of coatwith the container 5 and the supporting struc- .ture therefor may suitably comprise a pair of spaced parallel fingers 6a projecting over the floating die and preventing the die from travelling upwardly with the wire. The wire with a uniform layer of coating composition of the desired thickness thereon is passed upwardly from the die through a drying or baking oven 1 provided with electric heating units 8 supported within the insulated oven walls 9. Of course, it will be understood that any suitable design of baking oven may be employed, and that such oven may be. heated with gaseous combustion products, or by any other suitable means instead of the electric heating elements shown. The baked wire with its heat-hardened insulating coating thereon is passed over a driving sheave l0 and is either recirculated through the coating material,

The numeral 6 designates generally a ing material or is passed over pulley H to a takeup reel (not shown).

The die of this invention comprises two substantially L-shaped or right-angle members with mean at the extremities of these members for slidably interlocking themto form a rectangular die opening therebetween. As the two members are movable with respect to one another, the die readily adapts itself to the surface contour of the wire passing therethrough.

The structure of such a die is best understood by reference to Figs. 2 and 3 of the drawing. The die shown therein comprises two right-angle or L-shaped sections or members l2 and I3 adapted to interleave at their extremities to form the rectangular die opening ll. Each of the sections l2 and I3 may suitably comprise a plurality of thin, vertically stacked, right-angle or 'L-sh'aped laminations l5 and It spaced from one another by a number of relatively short-armed or rectangular spacers l1 and. i3 -as thick as or slightly thicker than the laminations ,ol the other L-shaped section. Rivets l9 and passing. vertically through the stacked laminations and spacersof each section integrally unite each set or section of stacked laminations andspacers" into a rigid structure.

pansion and thus the accommodation of correspondingly larger wire, is possible up to the point where the extremities of the L-shaped sections are no longer in interlocking'or interleaving relation about thewire.

A second embodiment of the invention is shown in Figs. 4 and 5. In this embodiment the two die sections 26 and'2l are made up of sets of laminations 23 and 23 thicker and fewer in number than the corresponding laminations of the die shown in Figs. 2 and 3 and a number of raised projections 33 and 3| are provided on the inner edges of some or all of the laminations which projections serve as runners to center the wire within the die. By this arrangement the projections 33 and 3| may extend over the whole inner edge of each L-shaped lamination-including the portions ordinarily interleaved with the corresponding laminations of the other die section so that an exact centering of comparatively wide 01: thick rectangular wire is assured. If deshed, the projections on some of the laminations,

The spacers alternatively interposed between the laminations serve to space the ends or extremities of the various laminations comprising each section to permit the interlocking or interleaving of the laminations of one section with those of ,the other section to form an assembled die structure having a rectangular opening capable of accommodating wire I as shown in Fig. 2.

Self-centering means, provided on the inner surface of the die opening, serve to center the wire within the die opening. A plurality of runners such as fine steel wires 2| and 22 placed substantially perpendicular to the plane of the laminations and suitably secured, as by soldering, to therespective sections I2 and I3, may be used for this purpose.' After the two sections are assembled about wire I, they are held in resilient interleaving engagement by any suitable means as for example helical spring 23 in the form of a ring encircling the assembled sections and resting in grooves 2| and 25 provided in the outside corners of L-shaped sections l2 and I3.

,The spring 23 or some other suitable device capable of producing the same result thus holds runners 2| and 22 in continual frictional engagement with wire I during the passage of the wire through the opening I 4. As the runners closely follow any variations in the surface contour of the wire, a layer of coating material of uniform thickness is applied to the wire over its entire length. The thickness of the layer is controlled by the diameter of the wire used in forming runners 2| and 22. Ordinarily the diameter of these runners is such that a layer of enamel having a thickness of a few thousandths of an inch or less is applied to the wire during each passage thereof through the apparatus. The die is adiustable to take any size wire above a certain minimum size corresponding to the size of the die opening when the interleaved laminations of one section bear against the edges of the spacers of the other die section. Thus the minimum size wire accommodated by any specific die will depend upon the length of the spacer arms which may in certain cases be zero, 1. e., the spacers may be rectangular in shape. With wire of larger cross-section,- the die expands against the pressure of the spring ring 23 and this ex-' such as the center lamination, of, each section may be staggered with respect to those of the remaining laminations.

The'laminations 30 and 3| are spaced by suitable spacers 32 and 33. Each of the die sections '26 and 21 are provided with two rodshaped projections 34 and 35 extending outwardly from the center of the two arms of the L- shaped sections. The ends of these projections are grooved to receive asecuring spring ring 31 Y corresponding to spring 23 in Fig, 2. Preferably,

but not necessarily, the outside edges of the sections are beveled to prevent contact of spring to rods 3| and 35 so, that all of the contracting forces ofthe spring aredirected perpendicular to the respective plane surfaces of the die opening and the wire; Rivets or bolts 33 and 39 integrally unite the laminations and spacers of each section. .i

In the modification shown in Fig. 6, the-two interlocking die sections. 40 and ll of stacked laminations l2 and 43. and spacers M and 45 are so constructed that with no wire inserted in the die opening, the annular spring 46 lying in the grooved edges of the die sections will pull the interleaved sections together and completely close the die opening. This complete closing of the die opening is possible in this modification of the invention due to the proper selection of the size and shape of the respective interleaving laminations and spacers. As shown in the drawing. each of the laminations of one section and each of the opposing spacers of the other section are complementary portions of a circular disk so that when completely closed, the assembled die is of circular shape. The stacked laminations of each section are suitably held firmly together by means of rivets 41 and 48. Wire or die spacing means 43 comprising minute projections are provided on those edges of the laminations adapted to the die opening. Obviously by varying the relative sizes and shapes of the stacked laminations and spacers variable die openings of any. minimum or maximum size or shape may be obtained. A die of the specific structure shown in Fig. 6 can be used in coating rectangular wires of relatively great width as compared with the thickness thereof.

In all modifications the die sections are of sufficient height to prevent tilting of the die with respect. to the wire.

It will be seen that the present invention makes practical the utilization of highly viscous wire enamels in the coating of rectangular wires of various sizes and shapes.

What we claim as new and desire to secure by Letters Patent of the United States, is:

1. Adie for use in coating wires of substantially rectangular cross-section with liquid coating material, said die comprising two L-shaped sections, at leastpart of the extending portions of each of said L-shaped sections comprising a plurality of spaced parallel flat fingers inter-' .leaved with the opposite spaced parallel fingers of the other of the two L-shaped sections, the two 'L-shaped sections cooperating to form a substantially rectangular die opening and being free to move with respect to one another to vary the size of said die opening, means on the interior surfaces of said L-shaped section for cenular wire, said assembly comprising two stacks of spaced, L-shaped laminations, the extending portions of the L-shaped laminations of one stack being interleaved with the extending portions of the L-shaped laminations of the second stack e"ch of said stacks of L-shaped laminations being freely movable with respect to the other stack, and means comprising a spring for holding said stacks in operating position about said wire.

4. An expansible die for use in coating substantially rectangular wire comprising a plurality of stacked L-shaped laminations, alternate L- shaped laminations facing oppositely to the remaining L-shapedlaminations and being slidably interleaved therewith at their extending end portions, each of the sets of said alternate laminations having spacers therebetween at the rightangle portions of the Us adapted to provide spaces between the end portions of the lamina,- tions of one set for the interleaving of the end portions of the laminations of the second set, means for integrally uniting the laminations and spacers of each of said sets into a rigid structure, means for holding said sets in resilient interleaving engagement'with each other and with the wire to be coated, and means for-maintaining a predetermined space relation between each of said sets and said wire.

5. A die for use in coating wires with liquid coating material, said die comprising two angle sections, at least part of the extending portion of each of said angle sections comprising a plurality of spaced parallel fingers interleaving with the opposite spaced parallel fingers of the other of the two angle sections, the two angle sections cooperating to form a die opening and being free to move with respect to one another to vary the size of said die opening, and means for holding said angle sections in operative position b to form a substantially rectangular die opening,

about the wire.

6. A die for use in coating wires with liquid coating material comprising, in combination, a plurality of members, each member having diverging arms, the arms of-each member comprising a plurality of spaced parallel fingers interleaving with the spaced parallel fingers of another arm, the members cooperating to form a die opening and being free to move with respect to one another to vary the size of said die opening in accordance with variations in the size of 

